Fey Wind was originally the ability that attracted me to SCH in ARR because it gave them one of the few (or only, I don't remember) dps boost support abilities in the game. Once AST came along in HW, the ability still felt unique because of it's on-use effect. Even if the effect was average or even below average compared to the pure dmg boost AST brought, it still provided an ability no other job in the game had.
While SCH's throughput has increased since ARR, I still feel like they're still missing something like Fey Wind to round out their arsenal - even if this ability is reworked a bit.
Lastly, and I'm possibly making a huge assumption here, I feel like making this change wouldn't require a significant amount of coding since it has existed as an ability in the past even if the faeries have been reworked a bit. I'd be interested in hearing other people's thoughts though!